Which chromosomal aberration results in the loss of a chromosome segment?

• A. Deletion
• B. Duplication
• C. Inversion
• D. Translocation

Answer: (A)

This question tests how chromosomal abnormalities affect the amount of genetic material. A deletion is when a part of the chromosome is removed, so genes in that region are lost. That’s exactly what is meant by the loss of a chromosome segment. In contrast, a duplication adds an extra copy of a segment, increasing material rather than removing it. An inversion rearranges the order of a segment without losing any genes, so the total amount of material stays the same. A translocation moves a segment to another chromosome, which rearranges where the genes are but doesn’t inherently remove them. So the deletion is the mechanism that causes the loss of a chromosome segment.